BACKGROUND: On the Danish island of Bornholm an intervention was carried out during 2008-2010 aiming at increasing out-of-hospital cardiac arrest (OHCA) survival. The intervention included mass media focus on resuscitation and widespread educational activities. The aim of this study was to compare the bystander BLS rate and survival after OHCA on Bornholm in a 3-year follow-up period after the intervention took place. METHODS: Data on OHCA on Bornholm were collected from September 28th, 2010 to September 27th, 2013 and compared to data from the intervention period, September 28th, 2008 to September 27th, 2010. RESULTS: The bystander BLS rate for non-EMS witnessed OHCAs with presumed cardiac aetiology was significantly higher in the follow-up period (70% [95% CI 61-77] vs. 47% [95% CI 37-57], p=0.001). AEDs were deployed in 22 (18%) cases in the follow-up period and a shock was provided in 13 cases. There was no significant change in all-rhythm 30-day survival for non-EMS witnessed OHCAs with presumed cardiac aetiology (6.7% [95% CI 3-13] in the follow-up period; vs. 4.6% [95% CI 1-12], p=0.76). CONCLUSION: In a 3-year follow-up period after an intervention engaging laypersons in resuscitation through mass education in BLS combined with a media focus on resuscitation, we observed a persistent significant increase in the bystander BLS rate for all OHCAs with presumed cardiac aetiology. There was no significant difference in 30-day survival.